Abstract: User interfaces and computer enabled methods for defining, discovering, and viewing map layers are provided. The map layers annotate an existing map by providing additional information that is not present in the existing map. A contribution user interface receives and configures the map layer on a web browser. The contribution user interface allows the map layer to be positioned over a desired location and displayed as a semi-transparent image overlay superimposed over the existing map. The map layer may be enlarged, reduced, and rotated to match the features of the existing map. The map layer is stored for use by other users. The layer may be retrieved by users who search for the desired location or for related or nearby locations. The layer may be displayed as a search result, and may be displayed for viewing by users as a partially-transparent image overlay over the existing map.